Dibenzimidazole diurea grease thickening agents

ABSTRACT

DIBENZIMIDAZOLE-DIUREA COMPOUNDS CORRESPONDING TO THE FORMULA:   2-((5-(R1-NH-CO-NH-)BENZIMIDAZOL-2-YL)-R3-),5-(R2-NH-CO-   NH-)BENZIMIDAZOLE   WHEREIN R1 AND R2 ARE HYDROCARBYL RADICALS AND R3 IS A HYDROCARBYLENE RADICAL, ARE HIGHLY EFFICACIOUS GREASE THICKENING AGENTS.

United States Patent ABSTRACT OF THE DISCLOSURE Dibenzimidazole-diurea. compounds corresponding to the formula:

wherein R and R are hydrocarbyl radicals and R is a hydrocarbylene radical, are highly efficacious grease thickening agents.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a novel class of dibenzimidazole-diurea compounds and grease compositions gelled therewith.

V Description of the prior art :It has become increasingly important that grease compositions be able to provide adequate lubrication at high temperatures, e.g., temperatures of 350 F. to 450 F. or higher. Numerous thickening agents have been proposed for use in such greases including soap base thickeners, inorganic clay thickeners and organic thickening agents. Examples of this latter class of thickening agents include various polyureas, ureido compounds, aminoaryl diureas, triazines and the like. Such organic thickening agents are typically prepared by reacting one or more mono-, di-, or polyamines with one or more mono-, di-, or polyisocyanates. Other related organic thickeners include arylcarbamyl compounds formed by reacting an aromatic amine with the reaction product of an aromatic diisocyanate and p-aminobenzoic acid.

While organic thickening agents of the aforementioned form satisfactorily at high temperatures. Other important 3,752,765 Patented Aug. 14, 1973 properties include thermal and mechanical stability, high temperature bearing performance, oxidation and corrosion resistance, etc. While additives are normally incorporated into grease compositions to improve one or more of these properties, the thickening agent itself can significantly affect, either favorably or adversely, the properties of the finished grease product. Thus, in spite ofthe numerous organic thickening agents known in the art, there is a continuing need for the development of thickening agents which will not only produce greases having high dropping points, but which will additionally augment other important properties of the finished product. The present invention provides such a class of thickening agents.

SUMMARY OF THE INVENTION It has now been found that grease compositions having excellent high temperature lubricating properties can be produced by incorporating into an oleaginous base .vehicle, a minor amount of a dibenzimidazole-diurea compound corresponding to the formula:

wherein R and R are hydrocarbyl radicals and R is a hydrocarbylene radical. (By hydrocarbyl or hydrocarbylene is meant monovalent or divalent organic radicals, respectively, comprising solely carbon and hydrogen. Such radicals may be aliphatic, acyclic or aromatic, or partially aliphatic and partially aromatic, e.g., alkaryl or aralkyl.) Not only do the grease compositions of the invention have high dropping points, but in addition they have excellent mechanical and thermal stability, and high temperature bearing performance properties as well. These excellent qualities are believed attributable in large part to the unique dibenzimidazole structure of the present thickening agents which produces an extremely stable molecule.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The aforedescribed dibenzimidazole-diurea thickening agents can be conveniently prepared by reacting One mole of a dicarboxylic acid or its anhydride with two moles of a nitro-substituted phenylenediamine, followed by reduction of the nitro groups to amine groups, and further reaction with two moles of a monoisocyanate. This procedure is illustrated by the following equations:

Equation 1 N0 NH, NO N0,- 2 o c C-Rs-C NH: \R/ v on OH i t \R/ Equation 2 N N N N NO N0, NHp- NH,

C-R3-C +6H] C-Ra-C 4H1 H H H H Equation 3 N N NH NH: o

. C-Rg-C R;--NO0 N N H H Dicarboxylic acids or anhydrides which can be suitably employed in preparing the thickeners of the invention include the acids or anhydrides of aliphatic dicar- 'boxylic acids such as succinic, glutaric, adipic, pimelic,

suberic, azelaic, sebacic acids or anhydrides; as well as aromatic dicarboxylic acids such as phthalic, isophthalic 'or terephthalic acids or anhydrides or their esters. Cyclohexanedicarboxylic acids or anhydrides are likewise suitable, e.g., 1,2- or 1,4-cyclohexanedicarboxylic acid or anhydride, and also tetrahydrophthalic acid or. anhydride. Hydrocarbyl substituted dicarboxylic acid and anhydrides can also be employed, for example, alkylor alkenylsubstituted succinic anhydrides corresponding to the formula 0 B-CH- HrC wherein R is an alkyl or alkenyl substituent of from 1 to 16 carbon atoms or more. Aliphatic dicarboxylic acids or anhydrides are preferred, and in general are selected so that the R, radical of the previously depicted formula has from 2 to 20,,preferably from 2 to 12 carbon atoms.

Phenylene diamines suitable for preparing the thicken ing agents of the invention are those having amino groups in the ortho position, i.e., o-phenylene diamines. When the thickening agents are prepared in accordance with Equation =1, o-phenylamine diamines having a nitro substituent must be employed, e.g., 4-nitro-o-phenylene diamine. In addition to the nitro substituent, o-phenylene diamines having other substituents, e.g., alkyl or halo substituents, can also be employed provided that such substituents do not appreciably interfere with the reaction of the phenylene diamine with the dicarboxylic acid or anhydride.

Phenylene diamines employed in accordance with the alternative procedure discussed above need not contain a nitro substituent since the addition of the nitro groups is accomplished subsequent to formation of the bis-benzimidazole. Hence, when this method of preparation is employed, unsubstituted o-phenylene diamine may be utilized or any other o-phenylene diamine having substituents which will not appreciably interfere with the formation of the bis-benzimidazole intermediate or its subsequent nitration. Examples of such ph'enylene diamines include 4-chloro-o-phen'ylene diamine and 3,4-toluene diamine.

Monoisocyanates which may be employed in accordance with the invention include aliphatic monoisocyanates or aromatic monoisocyanates having at least one aliphatic substituent of eight or more carbon atoms. Preferred monoisocyanate reactants include straight or branched chain, saturated or unsaturated aliphatic monoisocyanates having from 6 to 30, and more preferably from 12 to 24, carbon atoms. Examples of such isocyanates include cyclohexyl isocyanate, octyl isocyanate, decyl isocyanate, dodec'yl isocyanate, tetradecyl isocyanate, pentadecyl isocyanate, hexadecyl isocyanate, heptadecenyl isocyanate, octadecyl, isocyanate, octadecenyl isocyanate, eicosyl isocyanate, docosyl isocyanate, tetracosyl isocyanate and the like. Mixtures of the aforementioned isocyanates can also be employed including mixtures of saturated and unsaturated aliphatic isocyanates. Aliphatic isocyanates having 16 to 18 carbon atoms and mixtures thereof are particularly preferred. The R and R radicals in the aforementioned formula 'are derived from the monoisocyanate reactant.

The thickening agents of the invention are generally employed in grease compositions in an amount sufiicient to gel the oleaginous base vehicle'to grease consistency. This amount can vary, for example, from about 5-50% by weight of the total composition. Normally, however, thickener concentrations of |l0-35% by weight are sufficient to impart the desired consistency to the inventive compositions.

A wide variety of lubricating oils may be employed as the base vehicle in the present compositions. Suitable base oils include mineral'lubricating oils such as naphthenic base, parafiin base or mixed base oils having a viscosity in the range of from 50 SSU at F. to 300 SSU at 210 'F.; synthetic hydrocarbon oils such as oligomerized alpha-olefins and oils derived from coal products; synthetic oils such as alkylene polymers, alkylene oxide-type polymers, polyalkene glycols, polyethers, phosphate esters, dicarboxylic acid esters and pentaerythritol esters. The above oils may be used individually or in mixtures thereof, wherever miscible or made so by the use of solvents. Of the aforementioned base oils, mineral lubricating oils having viscosities of from about 400 to 700 SSU at 100 F. are especially preferred.

in addition to the dibenzimidazole-diurea thickeners, the present compositions can also contain anti-corrosion additives such as disodium sebacate, glyceryl monooleate, sodium sulfonates, sodium nitrite, aminoand beamtriazoles, and isostearamides or imidazolines of tetraethylenepentamines; oxidation inhibitors such as phenylalpha naphthylamine, phenyl beta naphthylamine, diphenylamines, phenothiaaine, dithiocarbamates, and

.various analogs and homologs thereof; viscosity index improvers such as methacrylate polymers and copolymers; extreme pressure agents, and any other additive recognized in the art to perform a particular function or functions.

The following examples illustrate the method of preparation of the present thickeners and their excellent properties. It is to be understood, however, that these examples are presented for illustrative purposes only and that the invention in its broader aspects should not be limited thereto.

EXAMPLE I A 4-liter round bottom flask was charged with 302.2 g. (2 moles) of 4-nitro-o-phenylene diamine, 100.0 g. (1 mole) of succinic anhydride and 2 liters of 4 normal hydrochloric acid solution. The flask and its contents were then refluxed, with stirring, for 24 hours. Heating was discontinued and the reactants were cooled to 0 C., filtered, and the filtrate was discarded. The precipitate was collected and neutralized with 1,500 ml. of 5 normal ammonium hydroxide solution, refiltered, and washed twice with water. The neutralized material resulting was dissolved in refluxing ethylene glycol, treated with decolorizing charcoal, filtered and the filtrate cooled. The

crystalline precipitate that appeared was collected, washed Federal Test Method Standard 791a, Method 333. The

with ethanol and dried. The yield was 65 grams of l ,2- bearing life-in these tests is expressedin hours and r epre1 bis(5-nitrobenzimidazoyl-2)ethane ha-vinga melting point sents the length of time until bearing failure occurred.

of 305 C. Test results are recorded in the following table.

56.04 g. (0.16 mole) of the above product was then 5 suspended in 1,200 ml. of 3 normal hydrochloric acid TABLE H solution to which was added palladium on charcoal Grease ot catalyst-and reduction of the nitro groups etfected in a low pressure hydrogenation apparatus. The catalyst was compo compo Test rocedureti 1 't' 6 then filtered off, the filtrate neutralized with sodium b1- 10 p on 51 carbonate and the resulting precipitate collected. After NflyHlghsPcedpeamg a 10-000 r.p.m., bearing life, hours 11,388 4,871 washing with water and drying, 41.5 g. of l,2-b1S( Pope Bearing Test, 350 F.,bearing life, hours 405 i was obtamed havmg 1 Includes 1% weight phenylalpha-naphthylamine, 0.5% Oronite 250 melting point Of 154-155 C. (dilauryl selenide), 1% weight sodium sebacate and 0.03% weight 3- 14.62 g. (0.05 mole) of the above material was placed amim'lvzvhmmleinto a 500-ml. resin flask equipped with a mechanical Mverage OHWO runs stirrer together with 30 g. (0.1 mole) of a 70:30 molar EXAMPLE IV ratio octadecyl isocyanate:hexadecylisocyanate mixture in 253 g. of HVl-SOO Neutral oil. This suspension was Other dibenzimidazole-diurea thickeners and greases heated with stirring, under nitrogen, to 127 C. Upon in accordance with the invention include those indicated completion of the reaction, the contents were cooled in the following table.

TABLE III Reactants ot- Grease Base composition Acid or anhydride Phenylene diamine Monoisocyanate 11 l 10 1,2-cyclohexane dicarboxylic anhydride.-. -nitro-o-phenylene diamine... 70% mole CzuHn N00, mole C|2H5NCO A Azelaic d do 70% mole C HuNCO, 30% mole CraHaz N OO. A

Dodecyl succinic anhy dfl mole CzzHoNCO B 13 Phthalic anhydride do 75% mole C1BH37NCO, 25% mole C H NCO E 1 See footnote at bottom of Table I.

to approximately 110 C. and then milled three times EXAMPLE V in a three-roll paint mill. The resulting grease had an ASTM dropping point of 510 F., and an ASTM worked During the preparation and testing of various greases penetration (60 strokes) of 272. based on the present thickening agents, it was found that EXAMPLE H thedibenzimidazole-diurea compounds the invention exhibit quite remarkable oxidation inhibiting activity when A series of grease compos tions containing varlous employed in conjunction with alkyl phenol or aryl aminedibenzimidazole drurea thickening agents in accordance 40 type antioxidants, particularly dior tri-alkyl phenols and with the luv ntl n were pr p r employing a y phenyl naphthylamines. This beneficial effect is demonof base vehicles. The reactants employed in the preparastrated by the results presented in Table IV which were tron of the respective thickeners and the propcrtles of obtained by subjecting samples of a mineral base oil conthe grease compositions gelled therewlth are pr s nt d taining the concentrations of antioxidants and thickening in Table 1. agent indicated in the table to an Air Oxidation Test at TABLE I Thick- Q1161 Reactants ofgorrcen- ASTM penetration ASTM Grease Acid or Phenylene Base iaeiglit Un- Worked ggi i composition anbydnde dtamme Isocyanate oil percent worked(Po) (Pm) F 1 Succinic 4I1it100 111018 CmHuNCO, 30% mole CisH:aNCO A 15 250 272 510 anbydride. pheuylene diamine.

100 7. mole CraHuNCO.-. B 14 290 100% mole CuHuNCO B 11 260 70% mole CisHuNCO, 30% mole CruHzaNCO B 15 276 63% mole CisHnNCO. 27% mole CmHaaNCO, A 14 279 10% mole CnHuNCO.

70% 111010 C18H31NCO, 30% mole CuHzzNCO D 10 234 70% mole CiaHnNCO, 30% mole C H NCO E 16 253 100% mole CrzHzsNCO C 15 257 Norm-Base oil- -A=Mineral lubricating oil having a viscosity oi 500 SSU at 100 F., B =Mineral lubricating oil having a viscosity of 70 SSU at 210 F C=Oligomer1zed alpha-olefin synthetic hydrocarbon oil having a viscosity of 7.7 centistokes at 210 F., D=Mineral lubricating oil having a viscosity of 430 SSU at 100 F., E=Mixture oi hexadecyl isostearate and dimer acid esters.

EXAMPLE III 350' F. In this test 9 liters of air per hour pass through 100 g. of the test sample to which is added 20 p.p.m. of

I order to demonstrate h excellcnt hi h tempmasoluble iron. The emergent air, after removal of contamiture performance characteristics of dibenzirnidazole-diants, is Passed through P Y analyzer which records urea thickened grease Compositions, Several of the greases t0 the oxygen content of the air. Using a reference air stream, of Example II Containing conventional oxidation and the rate of oxygen uptake is calculated. The test result which is called an induction period is defined as the time con-03mm mhlbltors were Sublected to the Navy High in hours required for one millimole of oxygen to be ab- SPeed Bearing Test as described in Fedfiral Test Method sorbed by the sample. A sample temperature of 350 F. 331.1, and to the Pope Bearing Test as described in was used in these tests.

1 Oetylated phenyl-alpha-naphthylamine; Thickener of Grease Composition 1.

I claim as my invention:

1. A grease composition consisting essentially of a major amount of an lubricating oil base vehicle and in an amount sutficient to thicken the base vehicle to grease consistency, a dibenzirnidazole-diurea compound corresponding to the formula:

wherein R and R are hydrocarbyl radicals having 6 to 30 carbon atoms and R is a hydrocarbylene radical having from 2 to 20 carbon atoms.

2. The composition of claim 1 wherein the dibenzimid- 8 azolediurea compound is present in the amount of from 5 to 50% by weight.

3. The composition of claim 1 wherein R and R are aliphatic hydrocarbyl radicals having from 12 to 24 carbon atoms. I v

4. The composition of claim 3 wherein R is an alkylene radical having from 2 to 12 carbon atoms.

5. The composition of claim 4 wherein the R and R radicals have from 16 to 18 carbon atoms.

6. The composition of claim 5 wherein R is ethylene.

7. The composition of claim 1 wherein the base vehicle is a mineral lubricating oil.

8. The grease composition of calim 1 having incorporated therein an oxidation inhibiting amount of a phenyl naphthylamine or (11- or tri-alkyl phenol antioxidant.

References Cited UNITED STATES PATENTS 3,015,625 1/1962 Rosscup et a1. 252-515 AX 3,133,883 5/1964 Hayne et al 2525l.5 A 3,222,285 12/1965 Rai et a1 2'525O X PATRICK P. GARVIN, Primary Examiner A. H. METZ, Assistant Examiner US. Cl. X.R. 260-309.2 

